The flu vaccine protects you from four strains of the influenza virus - two type A viruses, called A/H1N1 and A/H3N2 and two type B influenza viruses, called B/Yamagata and B/Victoria.

"These are the groups of viruses that we will see in the coming year," Prof Hurt said.

How do I get the vaccine?

Many workplaces offer a free flu vaccine for employees, but if yours doesn't and you're an otherwise healthy person, you can get one from your local GP for around $15, plus the cost of the doctor's consultation fee if they don't bulk bill.

The vaccine is free for some "at-risk" people under the National Immunisation Program.

Those included in the program are:

• People aged 65 years and over;

• Aboriginal and Torres Strait Islander people aged six months to less than five years;

• Aboriginal and Torres Strait Islander people who are aged 15 years and over;

• Pregnant women;

• People aged six months and over with medical conditions such as severe asthma, lung or heart disease, low immunity or diabetes that can lead to complications from influenza; and

• This year several states (Tasmania, Victoria, New South Wales, Queensland, Western Australia and the ACT) have expanded their free vaccine offering to children under five years of age.

How does the vaccine differ this year?

Aside from kids under five being included in the free program, two new "enhanced" vaccines have been created for people over 65 years old, a particularly at-risk group.

"Particularly in the elderly, the influenza vaccine was not as effective as we hoped it would be," Prof Hurt said.

"The real advantage of those two new vaccines for over 65s is they will provide an enhanced immune response and better protection for that group of patients. They are the ones we are most worried about protecting and the ones where the normal vaccines tend not to work quite so well," he said.

Can the vaccine really give you the flu?

No. It's physically impossible.

"The flu vaccines that are available in Australia are inactivated viruses," Prof Hurt said. "It is impossible for the vaccine to cause an infection because the viruses themselves are dead - they have been killed."

Then why do some people get sick after having a flu shot?

Getting "sick" or getting a cold is very different to contracting full-blown influenza.

"The time of year when people are getting vaccinated is often at the end of autumn and the start of winter and there are lots of bacteria and illnesses circulating that can cause similar symptoms," Prof Hurt said.

"It's probably one of these other viruses. They might think 'this vaccine has caused me to become ill', but they have been hit by another infection," he said.

"It's also important to note that it can take two weeks to develop immunity after you get the shot. It won't give you immediate protection and it lasts for about six to nine months."

I'm fit and healthy. Do I really need the vaccine?

Yes, because even healthy people are being severely affected, even killed by the flu.

"Although the risk is low for otherwise fit and healthy people there is a risk nonetheless.

"More and more what we see is that it is hard to predict who will become severely ill with influenza," Prof Hurt said.

"Of those kids hospitalised last year, about half of them didn't have any underlying illnesses. Fit and healthy people including children can still become severely unwell or be hospitalised."